Earth-sky projectors are used in simulators to provide a realistic visual representation of the environment, including the earth and sky. The projectors are normally servo controlled by computer inputs to rotate the visual scenes as required to duplicate the motion of a simulated vehicle. In sky projectors the light source is normally a mercury arc lamp, and in earth projectors the light source is normally a tungsten halogen lamp. In either case the light is projected through a dyed transparent hemispherical dome, to a screen. The prior art hemispherical domes are made of glass or of an acrylic plastic material and are dyed by spraying the inside, and in some cases the outside, or by dipping the outside surface in a dye vat and slowly removing it to provide color density variation increasing from light to dark from the horizon to the zenith point of the hemisphere. The color density variation achieved by spraying or dipping is not uniform and therefore is not adequate for today's sophisticated simulators. Further, when the dyed surface is the inside surface of the dome the surface will craze and the dye will fade rapidly when subjected to ultraviolet rays emitted from mercury arc lamps. However, we have discovered that cast thermoplastic acrylic has excellent ultraviolet absorbing characteristics and that the usable life of simulator hemispherical domes can be extended by approximately a factor of eight when made of acrylic plastic and the dyed surface is the outside surface of the hemispherical dome.